1. Field of the Invention
The present invention relates to a construction machine such as a motor grader, a rough terrain crane, a power shovel, a wheel loader, a bulldozer and others, or a working vehicle such as a dump truck, a forklift and others, and a speed control method thereof. Further, the present invention relates to a variable power engine capable of changing its power and a power setting method thereof, the engine being used in the above vehicles. Furthermore, the present invention relates to a vehicle with a variable power engine such as described above and a power control method thereof.
2. Description of the Related Art
Recently, in a working vehicle, e.g., a machine such as a motor grader, a gear-contained transmission with an electronically controlled clutch having a gear train and a plurality of hydraulic (fluid pressure) clutches, combination of which can be changed in various ways, is used, and the gear-contained transmission with the clutch controlled by a solenoid operated valve to carry out various operations is increasing.
(Inching Pedal)
In a motor grader, a special work such as leveling the ground by using a blade while turning a corner may be performed. In such a case, a number of revolutions of the engine must be increased in some measure and, in this high velocity revolution, the vehicle speed is also increased from the nature of the case, which makes it difficult to turn a corner while carrying out the necessary work. Therefore, there is a request for reducing the vehicle speed while maintaining the high velocity revolution.
In order to satisfy such a request, a foot-operated inching pedal (clutch pedal) is provided, and stepping on this inching pedal can slide a predetermined clutch of the transmission to decrease the speed, thereby filling the needs of a necessary work and turning a corner and the like.
In case of the working vehicle, when starting the machine from standstill, since starting is possible from a relatively high speed stage as different from a general vehicle, the machine is started at a plurality of speed stage positions. When starting at different speed stage positions in this manner, since an input shaft is different from an output shaft in speed reducing (speed increasing) ratio for each speed stage position, the connection state of the clutch differs even though the inching pedal is stepped on at a similar angle. In other words, when the inching pedal stepping angle is unchanged, the machine can be started and travel at a desired speed at a low speed stage position, whilst the machine can not be started or travel at a lower speed than expected at a higher speed stage position. Therefore, there is a problem that a desired speed can not be obtained unless the inching pedal stepping angle is reduced (unless the pedal is released) at the higher speed stage position.
As a technique for equaling the feel of stepping on the inching pedal which differs in accordance with each speed stage position, there is an invention disclosed in Japanese patent laid-open publication No. Hei 10-246318.
In the invention disclosed in this publication, a solenoid working pressure regulating valve is provided to each clutch constituting each speed stage of the transmission; one solenoid operation manual regulating valve (proportional valve) is provided to some regulating valves out of the above pressure regulating valves on the upstream side; and each valve is controlled by a controller in accordance with an inching pedal stepping angle and a speed stage position, thereby controlling the connecting force of the clutch to be controlled in accordance with a change in the speed stage (selected gear ratio).
According to the invention disclosed in this publication, since the connecting force of the clutch is changed in accordance with the speed stage position, the inching pedal stepping position can be roughly associated with the speed of the machine irrespective of the speed stage position of the transmission, but an input number of revolutions and an output number of revolutions of the transmission are not monitored at all, and the sufficient (detailed) control of the output shaft, i.e., the vehicle speed can not be necessarily performed.
Further, since the pressure regulating valve of each clutch is controlled by one proportional valve provided on the upstream side thereof, there is also such a problem as that the detailed control of each clutch is not necessarily adequate.
(Hyper-slow Mode)
In the motor grader, a work for finishing the road surface or the bank with the extremely high accuracy may be carried out. In such a case, there is a request for realizing the very low speed of, e.g., approximately 1.0 km/h from the necessity of the work.
On the other hand, as to a number of revolutions of the engine, the high speed revolutions in some measures is required from the necessity of the work and, in such a high speed revolution, the vehicle speed is necessarily increased, which makes it difficult to realize the very low speed running while carrying out the necessary work. Therefore, there is a need for decreasing the vehicle speed while maintaining the high speed revolution.
In order to satisfy the above needs, there have been proposed many variable displacement torque converters, i.e., torque converters capable of automatically converting attitudes or shapes of three vanes, namely, an impeller, a turbine vane and a stator of the torque converter in accordance with a range of the high and low speeds.
With the working vehicle having the above-described variable displacement torque converter, running at a very low speed and a predetermined finishing operation can be efficiently carried out.
However, since the variable displacement torque converter has the complicated structure, it is very expensive, resulting in an increase in the price of the vehicle itself.
Further, the rising interest in the recent environmental concerns leads to an issue of noise reduction of the working vehicle.
That is, a number of steady-state revolutions of a conventional engine is determined to be approximately 2,500 RPM and a number of revolutions in the low idling is determined to be approximately 800 RPM.
On the other hand, in view of the noise reduction, a number of steady-state revolutions of approximately 2,000 RPM and a number of revolutions in the low idling of 800 RPM are required. This brings up the following new problem when realizing the very low running such as described above.
That is, if a forward first speed in the first in forward in a conventional number of steady-state revolutions is set to, for example, 3.45 km/h, the vehicle speed in the low idling becomes 1.1 (=3.45xc3x97800/2,500) km/h, which is the hyper-slow running with which the finishing work is possible.
Meanwhile, if a number of steady-state revolutions is set to 2,000 RPM without changing the structure of the transmission, the vehicle speed in the low idling becomes 1.38 (=3.45xc3x97800/2,000) km/h.
However, the vehicle speed of 1.38 km/h is too high for the finishing work using the motor grader.
Thus, a working vehicle having a simplified structure by which a number of steady-state revolutions of the engine can be reduced and the very low speed running is also enabled is desired.
(Variable Power Engine)
The following can be true to the above-described engine of a working vehicle.
An engine power is usually set so as to obtain a given fixed maximum power. However, there is a request for changing a set value of a maximum power in accordance with circumstances depending on vehicles and machines.
For example, in case of the construction machine, a large power directly relates to the high work efficiency. However, in a low speed range, since the speed decreasing ratio of the transmission is large, a large power may cause the drive force to exceed a road surface adhesive coefficient of a wheel or a crawler and, in such a case, the wheel or the crawler go into a slide. Slippage of the wheel and the like leads to difficulty in the work and the deteriorated drive controllability, and wear-out of the wheel and the like is caused to shorten the life, thereby degrading the work efficiency.
In order to prevent this, an appropriate power is determined in accordance with the speed stages of the transmission in a regular work area, for example. Thus, the engine can afford to output, but the engine power is suppressed in order to prevent slippage during the work in the low speed stage even though the highly efficient work is possible with more power when working in the higher speed stage.
In the above-described case, if the power is variable, an appropriate power can be selected in the work, thereby improving the work efficiency.
Therefore, there has been developed an engine (variable power engine) with which an engine power is variable by controlling fuel oil consumption. FIG. 31 indicates an example of running and rim pull performances of a general vehicle with a variable power engine. FIG. 31 indicates the relationship between a vehicle speed (horizontal axis) and a rim pull (vertical axis) of a vehicle having a six-speed change gear. The characteristic indicated by a solid line represents the character of all speeds from the first speed to the sixth speed in the state of the usual power (normal power), and the characteristic indicated by a broken line represents the characteristic of the high speed range from the third speed to the six speed in the high power state.
In such a vehicle, the land clearing work is conducted at the second speed; the work for scattering a material such as ballast, the work for leveling the gravel path and the light load work such as snow removal are carried out at the third to fifth speeds; and the running or lighter load work is performed at the sixth speed.
In this case, since slippage of the wheel and the like does not occur with the high power in the light load work or running at the third or higher speed, the engine power is set to the high power characteristic indicated by the broken line to conduct the highly efficient work.
There are currently known several methods for obtaining a variable power. For example, there are the following methods.
1) An electronically controlling method adopting electron governor control.
2) A method disclosed in U.S. Pat. No. 4,785,778. An apparatus used in this method has such a structure as that one end of a main governor spring is brought into contact with a movable rack controlling a fuel oil consumption of a fuel injection system while the other end of the main governor spring is associated with a control lever and a position of the control lever is changed by a hydraulic cylinder. When the position of the control lever is displaced by using the hydraulic cylinder in a direction for thrusting the main governor spring or in the opposed direction, a spring pressure is changed to control the fuel oil consumption.
3) A controlling method using a boost compensator. In this method, a supercharged pressure of a turbo charger to be applied to a boost compensator is subjected to on/off control by using an electromagnetic valve in an engine provided with a fuel injector having the boost compensator, and a high power state in which the supercharged pressure is supplied and a normal power state in which no supercharged pressure is supplied are set to obtain the two-stage engine power.
Regarding to each method described above, in the electronic governor of 1), a flexibility of the power setting is high but the price is high. Further, attachment on the spot (outdoor and field) and general repair by a serviceman in case of a failure are difficult.
As to the method 2) disclosed in the U.S. patent, the system has a relatively simple structure, and repair is easy, but on-the-spot retrofitting is difficult after distributed to a customer.
In the control 3) using the boost compensator, the system is inexpensive and simple, repair is easy and retrofitting is possible. However, the flexibility of the power setting is low, and since the supercharged pressure is subjected to only the on/off control, the intermediate power setting is impossible even if such setting is necessary. In addition, when turning off supply of the supercharged pressure to the boost compensator, since a duct connecting the turbocharger to the boost compensator is simply opened in the atmosphere, the air supercharged by the turbocharger is partially wastefully discharged in the atmosphere.
In a vehicle having a recent variable power engine, a torque converter provided between the engine and the transmission is often seen. However, in the vehicle having the torque converter, although the driving operation is facilitated, slippage in the torque converter occurs to decrease the mechanical efficiency of power transmission, and reduction is the efficiency during driving at the high speed stage becomes a problem in particular.
Accordingly, a torque converter having a lockup mechanism for directly coupling (locking up) the torque converter at the high speed stage was developed, and a motor grader provided with the torque converter having such a lockup mechanism is on sale from CATERPILLAR in US (see the catalog xe2x80x9c24H, Motor Graderxe2x80x9d, p. 192, 1996, CATERPILLAR).
However, the motor grader of CATERPILLAR does not take the relationship between the variable power engine and the lockup mechanism into account at all, and the satisfactory driving control is not realized.
Further, in order to make the running performance of the vehicle having the variable power engine further complete, an all wheel drive (AWD) type vehicle in which a driving wheel can be switched to all the wheels is on sale. This type of all wheel drive type motor grader is on market from JOHN DEERE in US (see the catalog xe2x80x9cMotor graders 770C, 770CH, 772CHxe2x80x9d, 1997, JOHN DEERE).
Although the motor grader of JOHN DEERE takes the relationship between the variable power engine and the all wheel drive into consideration, it does not include the torque converter or that having the lockup mechanism for improving facilitation of the running operation. This motor grader does not sufficiently enhance the operability and the controllability of the vehicle having the variable power engine.
An object of the present invention is to provide a working vehicle with which an operator can work without changing his/her feeling irrespective of a speed stage position in a transmission.
Another object of the present invention is to provide a working vehicle capable of performing detailed control in each speed stage position in a transmission.
Still another object of the present invention is to provide a working vehicle capable of selecting a degree of connection of a clutch mechanism by operating an inching pedal according to an operator""s preference.
In order to achieve the above aim, according to the present invention, a degree of connection (slip state) of a clutch mechanism by operating an inching pedal is controlled by monitoring an angle of an inching pedal, a speed stage position (shift position) of a transmission, and numbers of revolutions of the transmission on input and output sides.
Further, another objection of the present invention described above is attained by connecting an electronic control regulating valve (ECMV) to each clutch of the transmission.
Furthermore, still another object of the present invention described above is attained by adding a mechanism capable of selecting a degree of connection of the clutch mechanism by operating the inching pedal according to an operator""s preference.
Specifically, the present invention defined in claim 1 provides a working vehicle comprising: an engine; a gear-contained transmission with a clutch having a plurality of clutch mechanisms for converting revolutions of said engine into speed ratios of multiple stages and a gear train; a connection force control mechanism for controlling connection force in said clutch mechanism in said transmission; an inching pedal operated in order to generate a slip in a predetermined clutch mechanism of said transmission; an input side revolution detection mechanism for detecting a number of revolutions on an input side of said transmission to output an input side revolution signal; an output side revolution detection mechanism for detecting a number of revolutions on an output side of said transmission to output an output side revolution signal; a speed stage position detection mechanism for detecting a speed stage position of said transmission to output a speed stage position signal; a pedal angle detection mechanism for detecting a stepping angle of said inching pedal to output a pedal angle signal; and a transmission controller to which said input side revolution signal of said input side revolution detection mechanism, said output side revolution signal of said output side revolution detection mechanism, said speed stage position signal of said speed stage position detection mechanism and said pedal angle signal of said pedal angle detection mechanism are inputted and which outputs a connection force control signal to said connection force control mechanism based on said input side revolution signal, said output side revolution signal, said pedal angle signal and said speed stage position signal in such a manner that a number of revolutions on said output side in said transmission becomes a predetermined value.
According to the present invention, since a degree of connection (slip state) of the clutch mechanism is controlled by operating the inching pedal while monitoring an angle of the inching pedal and a speed stage position (shift position) of the transmission as well as numbers of revolutions of the transmission on the input and output sides, the clutch mechanism can be appropriately connected irrespective of the speed stage position.
In the present invention, the term xe2x80x9cspeed stage positionxe2x80x9d is used as a concept including forward and reverse directions. Further, the input side and the output side of the transmission do not necessarily indicate an input and an output of the transmission itself but means the sides which the clutch mechanism generating slippage is engaged to or released from. That is, if the transmission has a plurality of shafts and the clutch mechanism is provided to each shaft, when slippage is generated in one or more clutch mechanisms associated with a first shaft and a second shaft for example, the first shaft is on the input side and the second and the subsequent shafts are on the output side. Therefore, a number of revolutions on the output side can be detected by using the second and the subsequent shafts. This idea can be applied to detection of a number of revolutions on the input side when the shaft associated with slippage is the second or the subsequent shafts. That is, the upstream side of the clutch mechanism associated with slippage corresponds to the input side and the downstream side of the same to the output side.
In the working vehicle according to claim 1, the present invention defined in claim 2 provides a working vehicle, wherein said controller is provided with: an actual speed ratio calculating function for calculating an actual speed ratio in said transmission from a ratio of said input side revolution signal and said output side revolution signal; a target speed ratio calculating function for calculating a target speed ratio in said transmission from said pedal angle signal; and a control signal transmitting function for outputting said connection force control signal to said connection force control mechanism from a difference between said target speed ratio and said actual speed ratio and said speed stage position signal in such a manner that said actual speed ratio becomes a predetermined value.
According to the present invention, the simple calculation in the controller can control slippage of the clutch mechanism.
In general, although the speed ratio means a ratio of a number of revolutions on the input side to a number of revolutions on the output side, in the present invention, basically, the speed ratio may be detected as a slip ratio since detection of the anteroposterior slip state of the clutch mechanism generating slippage is sufficient.
In the working vehicle according to claim 1, the present invention defined in claim 3 provides a working vehicle, wherein said controller is provided with: an actual speed ratio calculating function for calculating an actual speed ratio in said transmission from a ratio of said input side revolution signal and said output side revolution signal; a target speed ratio calculating function for calculating a target speed ratio in said transmission from said pedal angle signal and said speed stage position signal; and a control signal transmitting function for outputting said connection force control signal to said connection force control mechanism from said target speed ratio and said actual speed ratio in such a manner that said actual speed ratio becomes a predetermined value.
According to the present invention, the advantages similar to those of claim 2 can be obtained.
As a difference between the present invention and the invention defined in claim 2, a difference between the target speed ratio and the actual speed ratio is previously calculated to perform correction based on the speed stage position signal and an obtained correction signal is outputted from the controller to the connection force control mechanism as the connection force control signal in the invention defined in claim 2, whilst correction is carried out based on the speed stage position signal in advance when calculating the target speed ratio and the target speed ratio incorporating the content of the speed ratio position signal is compared with the actual revolution signal to output the connection force control signal to the connection force control mechanism in the present invention.
In the working vehicle according to claim 1, the present invention defined in claim 4 provides a working vehicle, wherein said connection force control mechanism is an electronic control regulating valve (ECMV) which is coupled to a predetermined clutch mechanism to be controlled among a plurality of said clutch mechanisms in said transmission and controls an amount of working fluid to said clutch mechanism in response to said connection force control signal from said controller.
According to the present invention, a working fluid quantity to the clutch mechanism can be controlled by the electronic control regulating valve (ECMV) capable of accurate control.
In the working vehicle according to claim 4, the present invention defined in claim 5 provides a working vehicle, wherein said electronic control regulating valve includes: a pressure control valve to which said connection force control signal from said controller is applied and which converts a pressure into a fluid pressure responsive to said signal; and a flow rate detection valve operated by a hydraulic pressure signal from said pressure control valve.
According to this invention, the further accurate control is possible.
In the working vehicle according to claim 1, the present invention defined in claim 6 provides a working vehicle, wherein said gear-contained transmission with said clutch includes a plurality of direction switching clutch mechanisms and a plurality of speed switching clutch mechanisms and a clutch mechanism for generating a slip in accordance with an operation amount of said inching pedal is said direction switching clutch mechanism.
In general, although the clutch mechanism for generating a slip requires satisfactory cooling means because of a large calorific value, the cooling means having the large cooling power may be provided only to the direction switching clutch mechanisms whose number is relatively small according to the present invention, thereby reducing the manufacturing cost.
In the working vehicle according to claim 1, the present invention defined in claim 7 provides a working vehicle, wherein said controller is designed to have a control function such that a number of revolutions on said output side becomes within a predetermined deviation.
According to the present invention, since control is carried out with a given allowance, hunching does not occur during the control.
In the working vehicle according to claim 1, the present invention defined in claim 8 provides a working vehicle, wherein to said controller is connected to a characteristic change mechanism by which a content of said connection force control signal to be outputted to said connection force control mechanism can be changed in accordance with a working condition, an operator""s preference and others.
According to the present invention, the slip state of the clutch mechanism can be appropriately changed in accordance with differences in the work condition or an operator""s preference.
Yet another object of the present invention is to provide a working vehicle and a speed control method thereof capable of inexpensively obtaining appropriate working power and hyper-slow running with a simple structure.
The present invention intends to attain the above aim by making a judgement upon whether the hyper-slow running is carried out by using the controller and controlling the connection force of the clutch mechanism in the transmission.
Specifically, the present invention defined in claim 9 provides a working vehicle comprising: an engine; a gear-contained transmission with a clutch having a plurality of clutch mechanisms for converting revolutions of said engine into speed ratios of a plurality of stages and a gear train; a connection force control mechanism for controlling connection force in said clutch mechanism in said transmission; an output side revolution detection mechanism for detecting a number of revolutions on an output side of said transmission to output an output side revolution signal; a speed stage position detection mechanism for detecting a speed stage position of said transmission to output a speed stage position signal; an accelerator pedal operated in order to increase a number of revolutions of said engine; an accelerator pedal angle detection mechanism for detecting a stepping angle of said accelerator pedal to output an accelerator pedal angle signal; and a transmission controller to which said output side revolution signal of said output side revolution detection mechanism, said speed stage position signal of said speed stage position detection mechanism and said accelerator pedal angle signal of said accelerator pedal angle detection mechanism are inputted, which makes a judgment upon whether a current mode is a hyper-slow running mode based on said output side revolution signal, said speed stage position signal and said accelerator pedal angle signal, and which outputs a connection force control signal to said connection force control mechanism in such a manner that a number of revolutions on said output side in said transmission becomes a predetermined hyper-slow value in case of said hyper-slow running mode.
According to the present invention, since the connection force of the clutch mechanism of the transmission is controlled by using the control signal from the controller through the connection force control mechanism, the hyper-slow running can be acquired with a simple structure.
In the present invention, the term xe2x80x9cspeed stage positionxe2x80x9d is used as a concept including the both forward and reverse directions.
In the working vehicle according to claim 9, the present invention defined in claim 10 provides a working vehicle, wherein said controller is provided with: a hyper-slow running mode judging function which determines said hyper-slow running mode when a vehicle speed calculated from said output side revolution signal is smaller than a predetermined speed, e.g., 2.0 km/h or 1.8 km/h larger than a hyper-slow target speed, e.g., 10 km/h, said accelerator pedal angle signal is in a standby mode and said speed stage position signal indicates a predetermined low speed stage position; and a control signal transmitting function for outputting said connection force control signal to said connection force control mechanism in such a manner that a vehicle speed set in said hyper-slow running mode is obtained when said hyper-slow running mode is determined by said hyper-slow running mode judging function.
According to the present invention, the slippage of the clutch mechanism can be controlled by simple calculation in the controller, thereby obtaining the necessary hyper-slow running.
In the working vehicle according to claim 9, the present invention defined in claim 11 provides a working vehicle, wherein said connection force control mechanism is an electronic control regulating valve (ECMV) which is coupled to a predetermined clutch mechanism to be controlled among a plurality of said clutch mechanisms of said transmission and which controls an amount of working fluid to said clutch mechanism in response to said connection force control signal from said controller.
According to the present invention, the working fluid quantity to the clutch mechanism can be controlled by the electronic control regulating valve (ECMV) capable of accurate control.
In the working vehicle according to claim 11, the present invention defined in claim 12 provides a working vehicle, wherein said electronic control regulating valve includes: a pressure control valve to which said connection force control signal from said controller is applied and which converts a pressure into a fluid pressure responsive to said signal; and a flow rate detection valve operated by a hydraulic pressure signal from said pressure control valve.
According to the present invention, the further accurate control is possible.
In the working vehicle according to claim 9, the present invention defined in claim 13 provides a working vehicle, wherein said gear-contained transmission with said clutch includes a plurality of direction switching clutch mechanisms and a plurality of speed switching clutch mechanisms and a clutch mechanism whose clutch connection force is controlled for generating a hyper-slow speed in response to said connection control signal from said connection force control mechanism is said direction switching clutch mechanism.
In general, although the clutch mechanism generating a slip requires satisfactory cooling means because of a large calorific power, provision of the cooling means having a large cooling power to only the direction switching clutch mechanisms whose number is relatively small can suffice the invention, thereby reducing the manufacturing cost.
In the working vehicle according to claim 9, the present invention defined in claim 14 provides a working vehicle, wherein said controller is designed to have a control function such that a number of revolutions on said output side becomes within a predetermined deviation.
According to the present invention, since control is performed with a predetermined allowance, hunching does not occur during the control.
The present invention defined in claim 15 provides a working vehicle comprising: an engine; a gear-contained transmission with a clutch having a plurality of clutch mechanisms for converting revolutions of said engine into speed ratios of a plurality of stages and a gear train; a connection force control mechanism for controlling connection force in said clutch mechanism of said transmission; a speed mode setting mechanism which can switch a vehicle speed to a normal running mode and a hyper-slow running mode and outputs a running mode signal; and a transmission to which said running mode signal is inputted from said speed mode setting mechanism and which outputs a connection force control signal to said connection force control mechanism in such a manner that a number of revolutions on an output side in said transmission becomes a predetermined hyper-slow value when said running mode signal indicates said hyper-slow running mode.
According to the present invention, the speed mode can be appropriately changed by the speed mode setting mechanism.
The present invention defined in claim 16 provides a vehicle speed control method for a working vehicle comprising: an engine; a gear-contained transmission with a clutch having a plurality of clutch mechanisms for converting revolutions of said engine into speed ratios of a plurality of stages and a gear train; a connection force control mechanism for controlling connection force in said clutch mechanism of said transmission; an accelerator pedal operated in order to increase revolutions of said engine; an output side revolution detection mechanism for detecting a number of revolutions of said transmission to output an output side revolution signal; a speed stage position detection mechanism for detecting a speed stage position of said transmission to output a speed stage position signal; an accelerator pedal angle detection mechanism for detecting a stepping angle of said accelerator pedal to output an accelerator pedal angle signal; and a transmission controller to which said output side revolution signal of said output side revolution detection mechanism, said speed stage position signal of said speed stage position detection mechanism and said accelerator pedal angle signal of said accelerator pedal angle detection mechanism are inputted, which make a judgment upon whether a current mode is a hyper-slow running mode from said output side revolution signal, said speed stage position signal and said accelerator pedal angle signal and which outputs a connection force control signal to said connection force control mechanism in such a manner that a number of revolutions on said output side of said transmission becomes a predetermined hyper-slow value in case of said hyper-slow running mode, wherein said clutch mechanism and said gear train of said transmission are constituted as a plurality of direction switching clutch mechanisms and a plurality of speed switching clutch mechanisms, and said direction switching clutch mechanism is constituted as a forward low speed clutch mechanism and a reverse clutch mechanism, and wherein the control by said controller in said hyper-slow running mode is effected by supplying a predetermined working fluid pressure to either or both of any clutch mechanism on a driving side of said forward low speed clutch mechanism and said reverse clutch mechanism and a clutch mechanism on an opposite side among said direction switching clutch mechanisms.
According to the present invention, since a predetermined working fluid pressure is supplied to both the driving side clutch mechanism and the opposite side clutch mechanism of either the forward low speed clutch mechanism or the reverse clutch mechanism in the direction switching clutch mechanism to be controlled, the both clutch mechanism are balanced to carry out the speed control, thereby easily realizing the hyper-slow running.
In the vehicle speed control method of a working vehicle according to claim 16, the present invention defined in claim 17 provides a vehicle speed control method for a working vehicle, wherein said control by said controller in said hyper-slow running mode comprises the steps of: (1) supplying a low working fluid pressure of a first stage to said both clutch mechanisms when a vehicle speed is a control target value or within a deviation obtained by adding a predetermined difference to said control target value; (2) maintaining, on one hand, supply of said low working fluid pressure of said first stage to said clutch mechanism on said driving side, and, on the other hand, increasing said working fluid pressure to said clutch mechanism on an opposite side of said driving side to serve as a braking force when said vehicle speed is higher than said control target value or said deviation obtained by adding said predetermined difference to said control target value; and (3) maintaining, on one hand, supply of said low working fluid pressure of said first stage to said clutch mechanism on an opposite side of said driving side and, on the other hand, increasing said working fluid pressure to said clutch mechanism on said driving side to serve as a speed increasing force when a vehicle speed is lower than said control target value or said deviation obtained by adding said predetermined difference to said control target value.
According to this invention, the hyper-slow running can be produced more accurately
In the vehicle speed control method of a working vehicle according to claim 16, the present invention defined in claim 18 provides a vehicle speed control method of a working vehicle, wherein said control by said controller in said hyper-slow running mode comprises the steps of: (1) supplying a low working fluid pressure for generating a slip in said clutch mechanism on said driving side when a vehicle speed becomes not more than a predetermined value larger than a control target value; and (2) causing a braking force to act as an appropriate value by increasing or decreasing said working fluid pressure having a predetermined difference in accordance with a fixed cycle to said clutch mechanism on an opposite side of said driving side when a vehicle speed is higher or lower than said control target value beyond a predetermined difference, and shifting from said hyper-slow running mode to said normal running mode when a vehicle speed becomes not less than a predetermined value larger than said predetermined value greater than said control target value for entering said hyper-slow running mode.
According to the present invention, the hyper-slow running can be further accurately realized.
In the vehicle speed control method of a working vehicle according to claim 16, the present invention defined in claim 19 provides a vehicle speed control method for a working vehicle, wherein said control by said controller in said hyper-slow running mode comprises the steps of: (1) supplying a low working fluid pressure for generating a slip in said clutch mechanism on said driving side when a vehicle speed becomes not more than a predetermined value larger than a control target value; and (2) causing a braking force to act as an appropriate value by increasing or decreasing a working fluid pressure suitable for a deviation between said actual vehicle speed and said target vehicle speed to said clutch mechanism on an opposite side of said driving side when a vehicle speed is higher or lower than said control target value beyond a predetermined difference, and shifting from said hyper-slow running mode to said normal running mode when a vehicle speed becomes not less than a predetermined value larger than said predetermined value greater than said control target value for entering said hyper-slow running mode.
According to the present invention, the hyper-slow running can be further accurately realized.
A further object of the present invention is to provide an inexpensive variable power engine which has a simple structure and facilitates repair and retrofitting and which has a relatively high flexibility of power setting, and a power setting method thereof.
In order to attain the above object, the present invention provides a variable power engine, wherein a pressure state switching mechanism which can switch between and supply a reference pressure to be supplied to a boost compensator and at least a first-stage predetermined pressure decreased to be lower than the reference voltage is provided in a manifold for supplying a charged pressure (output side pressure) of a turbocharger to a fuel injector having a boost compensator, and the pressure state switching mechanism is switched in accordance with a speed stage position signal of a transmission.
In order to attain the above object, the present invention provides a power setting method of a variable power engine, wherein the charged pressure of the turbocharger is supplied to the boost compensator as at least a two-or-more-stage predetermined pressure which is equal to or lower than the charged pressure and higher than an atmospheric pressure in accordance with the speed stage of the transmission.
Specifically, the present invention according to the modification of the sixth embodiment provides a variable power engine comprising: a turbocharger for supplying a charged pressure to an engine; a fuel injector with a boost compensator for adjusting a fuel oil consumption in accordance with said charged pressure of said turbocharger; a transmission for changing output revolutions of said engine to a plurality of speed stages; a manifold for supplying said charged pressure of said turbocharger to said boost compensator; a pressure state switching mechanism which is provided to said manifold and capable of switching a pressure to be supplied to said boost compensator to predetermined pressures of at least two stages equal to or lower than said charged pressure of said turbocharger and higher than an atmospheric pressure; and a speed stage position detection mechanism for detecting a speed stage position of said transmission to supply a speed stage position signal to said pressure state switching mechanism, said pressure state switching mechanism being caused to perform pressure state switching operation by said speed stage position signal supplied from said speed stage position detection mechanism.
According to the present invention, since the supply pressure to the boost compensator can be changed to a predetermined set pressure to be supplied by the pressure state switching mechanism, an engine power matched with the operation content can be obtained, thereby improving the work efficiency.
In the variable power engine according to the modification of the sixth embodiment, the present invention provides a variable power engine, wherein said pressure state switching mechanism comprises: a hydraulic circuit device which is provided to said manifold and demonstrates a resistance action or a pressure decreasing action with respect to said manifold; an auxiliary manifold branched off between said hydraulic circuit device and said boost compensator in said manifold; and switching means which is provided to said auxiliary manifold and capable of switching between a state in which said auxiliary manifold is blocked and a state in which a pressure of said auxiliary manifold is released and a pressure to be applied from said turbocharger to said manifold is decreased to be a predetermined pressure of at least one stage lower than said pressure and higher than an atmospheric pressure.
According to the present invention, since the auxiliary manifold is provided to the manifold for supplying the charged pressure of the turbocharger to the boost compensator and the switching means for switching between the state in which the auxiliary manifold is blocked and the state in which the pressure is decreased to a predetermined pressure lower than the charged pressure, the predetermined pressure can be set with a simple structure.
In the variable power engine according to the modification the the sixth embodiment, the present invention provides a variable power engine, wherein said hydraulic circuit device provided to said manifold is constituted by a throttle.
According to the present invention, the hydraulic circuit device can have a very simple structure and provided inexpensively.
In the variable power engine according to the modification the the sixth embodiment, the present invention provides a variable power engine, wherein said switching means provided to said auxiliary manifold is constituted by a two-position selector valve capable of switching between a duct blocking state and a communicating state and a throttle provided to a duct on a slip stream side of said two-position selector valve in said communicating state of said two-position selector valve.
According to the present invention, the switching means can be constituted by a simple mechanism and inexpensively provided.
In the variable power engine according to the modification the the sixth embodiment, the present invention provides a variable power engine, wherein said slip stream side of said auxiliary manifold is connected to a duct on an upstream side of said turbocharger.
According to the present invention, when supplying a pressure decreased to be not more than the reference pressure to the boost compensator, the pressure flowing from the auxiliary branch circuit can be assuredly flowed back to the turbocharger side, eliminating the wasteful outflow of the pressure.
In the variable power engine according to the modification the the sixth embodiment, the present invention defined in provides a variable power engine, wherein said pressure state switching mechanism is caused to switch to said state for blocking said auxiliary manifold when said speed stage position signal supplied from said speed stage position detection mechanism is a high speed stage position signal.
According to the present invention, a light work operation at a high speed can be assuredly automatically performed with a high power in accordance with the speed stage position.
The present invention as disclosed in the modification to the seventh embodiment provides a variable power engine comprising: a turbocharger for supplying a charged pressure to an engine; a fuel injector with a boost compensator for adjusting a fuel oil consumption in accordance with said charged pressure of said turbocharger; a transmission for changing output revolutions of said engine to a plurality of speed stages; a manifold for supplying said charged pressure of said turbocharger to said boost compensator; a pressure state switching mechanism which is provided to said manifold and capable of switching a pressure to be supplied to said boost compensator to a pressure equal to said charged pressure of said turbocharger and a predetermined pressure of at least one stage lower than said charged pressure and higher than an atmospheric pressure; and a speed stage position detection mechanism for detecting a speed stage position of said transmission to supply a speed stage position signal to said pressure state switching mechanism, said pressure state switching mechanism being caused to perform pressure state switching operation by said speed stage position signal supplied from said speed stage position detection mechanism.
According to the present invention, it is possible to obtain an engine power matched with a content of work as similar to the invention defined in the sixth embodiment modifications, thereby improving the work efficiency.
In the variable power engine according to the modification of the seventh embodiment, the present invention provides a variable power engine, wherein said pressure state switching mechanism provided to said manifold is constituted by a two-position selector valve capable of switching said communicating state of said manifold to two positions and a pressure reducing valve provided to at least one duct on a slip stream side of said two-position selector valve.
According to the present invention, the object of the present invention can be attained by providing a simple hydraulic circuit device to the branch circuit.
The present invention according the modification of the sixth embodiment provides a power setting method for a variable power engine, said variable power engine comprising: a turbocharger for supplying a charged pressure to an engine; a fuel injector with a boost compensator for adjusting a fuel oil consumption in accordance with said charged pressure of said turbocharger; and a transmission for changing output revolutions of said engine to a plurality of speed stages, wherein said charged pressure of said turbo charger is supplied to said boost compensator as predetermined pressures of at least two stages equal to or lower than said charged pressure of said turbocharger and higher than an atmospheric pressure to set an engine power in accordance with a speed stage position of said transmission.
According to the present invention, a pressure supplied to the boost compensator can be readily set to two or more stages between the charged pressure and the atmospheric pressure, thereby easily obtaining a desired engine power.
In the power setting method of the variable power engine according to the modification of the sixth embodiment, the present invention provides a power setting method, wherein a pressure equal to said charged pressure of said turbocharger is supplied to said boost compensator to set an engine power when a speed stage position of said transmission is a high speed stage position.
According to the present invention, a light work operation at a high speed can be assuredly carried out automatically with a high power.
In a vehicle with a variable power engine, a still further object of the present invention is to provide a vehicle with a variable power engine which can satisfactorily demonstrate performances of the variable power engine and has the excellent operability and a power controlling method thereof
In order to attain the above object, the present invention provides to a variable power engine a transmission with a lockup mechanism and an engine power controller for controlling power of the variable power engine by a speed stage position signal of the transmission and a lockup enabled/disabled signal of the lockup mechanism.
In addition to the above structure, the present invention further provides a wheel driving state switching mechanism for changing over a wheel to be driven among wheels of a vehicle, and a wheel driving state detection mechanism for detecting the switching state of the wheel driving stage switching mechanism to output a wheel driving state detection signal to an engine power controller, thereby further achieving the above object.
Specifically, the present invention defined in as disclosed in the eighth embodiment provides a vehicle with a variable power engine comprising: an engine; an engine power switching device for changing a power of said engine to a plurality of stages; a torque converter with a lockup mechanism coupled with an output side of said engine; a multi-stage speed change transmission couple to an output side of said torque converter; a lockup detection mechanism for detecting on/off of an operation of said lockup mechanism to output a lockup enabled/disabled signal; a speed stage position detection mechanism for detecting a speed stage position of said transmission to output a speed stage position signal; and an engine power controller to which said speed stage position signal from said speed stage position detection mechanism and said lockup enabled/disabled signal from said lockup detection mechanism are inputted and which outputs an engine power switching signal to said engine power switching device.
According to the present invention, the torque converter enables the further smooth driving; the lockup mechanism can further improve the driving efficiency at a high speed; and an appropriate engine power can be obtained in accordance with a speed stage position of the transmission and the on/off of the lockup of the torque converter.
In the vehicle with the variable power engine according to the eighth embodiment, the present invention provides a vehicle with a variable power engine, wherein a turbocharger for supplying a charged pressure to said engine is connected to said engine, and said engine power switching device includes: a fuel injector having a boost compensator for adjusting a fuel oil consumption to said engine in accordance with said charged pressure of said turbocharger; and a pressure state switching mechanism for switching a pressure to be supplied to said boost compensator to predetermined pressures of at least two stages.
According to the present invention, a power of the variable power engine can be readily switched by utilizing the charged pressure of the turbocharger.
In the vehicle with the variable power engine according to the eighth embodiment, the present invention provides a vehicle with a variable power engine, wherein a wheel driving state switching mechanism for switching which wheel among wheels of said vehicle is driven is coupled to said transmission, and said wheel driving state switching mechanism is provided with a wheel driving state detection mechanism for detecting a switching state of said wheel driving state switching mechanism to output a wheel driving state detection signal to said engine power controller.
According to the present invention, when the wheel driving state can be switched, the engine power can be optimally controlled in accordance to this wheel driving state.
The present invention as disclosed in the eighth embodiment provides a power control method of a vehicle with a variable power engine, said vehicle comprising: an engine; an engine power switching device for changing power of said engine to a plurality of stages; a torque converter with a lockup mechanism coupled to an output side of said engine; a multi-stage speed change transmission coupled to an output side of said torque converter; a lockup detection mechanism for detecting on/off of an operation of said lockup mechanism to output a lockup enabled/disabled signal; a speed stage position detection mechanism for detecting a speed stage position of said transmission to output a speed stage position signal; and engine power controller to which said speed stage position signal from said speed stage position detection mechanism and a lockup enabled/disabled signal from said lockup detection mechanism are inputted and which outputs an engine power switching signal to said engine power switching device, wherein said engine power controller controls said engine power switching device in such a manner that engine power is obtained on a high power side (high power state) when said speed stage position signal from said speed stage position detection mechanism indicates a higher speed stage position than a predetermined speed stage and controls said engine output switching device in such a manner that said engine power is obtained on said high power side at a higher speed stage position than said speed stage position switched to said high power side when said lockup enabled/disabled signal from said lockup detection mechanism is a lockup enabled signal.
According to the present invention, the power of the variable power engine can be optimally controlled by using the speed stage position of the transmission and on/off of the lockup of the torque converter.
The present invention as disclosed in the embodiment provides a power control method of a vehicle with a variable power engine, said vehicle comprising: an engine; an engine power switching device for changing power of said engine to a plurality of stages; a torque converter with a lockup mechanism coupled to an output side of said engine; a multi-stage speed change transmission coupled to said output side of said torque converter; a lockup detection mechanism for detecting on/off of an operation of said lockup mechanism to output a lockup enabled/disabled signal; a speed stage position detection mechanism for detecting a speed stage position of said transmission to output a speed stage position signal; a wheel driving state switching mechanism which is coupled to an output side of said transmission and switches which wheel among wheels of said vehicle is driven; a wheel driving state detection mechanism for detecting a switching state of said wheel driving state switching mechanism to output a wheel driving state detection signal; and engine power controller to which said wheel driving state detection signal from said wheel driving state detection mechanism, said speed stage position signal from said speed stage position detection mechanism and said lockup enabled/disabled signal from said lockup detection mechanism are inputted and which outputs an engine power switching signal to said engine power switching device, wherein said engine power controller controls said engine power switching device in such a manner that engine power is obtained on a high power side when said speed stage position signal from said speed stage position detection mechanism indicates a higher speed stage position than a predetermined speed stage, controls said engine power switching device in such a manner that said engine power is obtained on said high power side at a higher speed stage position than said speed stage position switched to said high power side when said lockup enabled/disabled signal from said lockup detection mechanism is a lockup enabled signal, and controls said engine power switching device so as to switch to said high power state at a lower speed stage position than a speed stage position switched to said high power side before a number of driven wheels is increased when said wheel driving state switching mechanism performs switching in a direction for increasing a number of driven wheels.
According to the present invention, the power of the variable power engine can be optimally controlled by using a speed stage position of the transmission, on/off of the lockup of the torque converter and a number of driven wheels among wheels.